This invention has priority rights based on Japanese Patent Application Nos. 4-289105 and 4-289106, filed Oct. 27, 1992, the contents of which are hereby incorporated by reference.
The invention relates to a structure for sealing a gap between confronting surfaces of a weather strip and a portion of the automobile body on which the weather strip is mounted. More particularly, the invention relates to an elastic seal member as well as to a method of forming such elastic seal member.
As used herein, the term "weather strip" refers to the portion of an automobile which is attached to closure portions such as hoods, doors, and sun roofs, and which prevents rain, wind, dust, sound, cold and hot air from entering the automobile. The term can include glass runs and the like.
In addition, the invention also relates to a trim having a U-shaped section with confronting clamp lips formed therein and having an adhesive seal band formed by charging a sealant into an inner groove thereof.
The term "trim" can also be called a "welt" and designates not only an integral trim body, but also a trim portion which forms the mounting base of a weather strip.
While the seal structure for a weather strip is described by an example of a corner portion C1 (see FIG. 2) located at a joint between a door sash 3 and a vertical frame 5 (see FIG. 1) for a mirror bracket in a door glass run 1 of a front door D1, the seal structure of the invention is not limited to such an example.
A portion of a glass run 1 is as shown in FIG. 2. A pair of bent seal lips 7, directed toward a bottom portion, are arranged inside the glass run. On both outer sides of the bottom portion are seal fins 9 serving also as members for holding the door sash 3. The bent seal lips 7 abut against both surfaces of a glass pane G, and the seal fins 9 abut against the groove bottom portion of the door sash 3, so that their sealing function can be performed.
The corner portion C1 is fabricated by molding so that the linear portions 11, which are formed by cutting an extruded product, are connected to one another in generally perpendicular relation.
As can be seen, extensions 9A, 9B of the seal fins 9 are formed on the corner portion C1. Since it is difficult to make the extension 9A into a fin-like form by conventional molding technology, the extension 9A is made rib-like, which is a shape which does not flexibly deform easily. Therefore, flexibility relative to the groove bottom portion of the door sash 3 is inadequate, thereby causing the rib-like extension 9A to have inferior sealability characteristics.
As can be discerned from FIGS. 2 and 3, the height of the gap formed between the door sash 3 and the vertical frame 5, i.e., between the metal plate portion of the automobile body and the bottom portion 1A of the glass run 1 must be larger in the middle of the corner portion C1 as compared with other locations. Therefore, to increase sealability, a seal structure has been proposed, which not only utilizes a first elastic seal member 13a bonded along almost the entire length of the corner portion C1, but also a second elastic seal member 13b that is shorter than the first elastic member. The two layers of the elastic seal members 13a and 13b are formed in the middle of the corner portion (see Japanese Utility Model Unexamined Publication No. 29420/1992).
A number of problems with this seal structure exist. For example, since a rather abrupt step is formed between the first elastic seal member 13a and the second elastic seal member 13b in the above-mentioned seal structure, its sealability becomes inadequate when a higher degree of sealability is required.
Furthermore, bonding of the elastic seal members 13a and 13b, which are made of a sponge sheet, involves a time-consuming manual operation which requires both hands with the glass run 1 fixed on a jig. In addition, since two layers of seal material must be used, the number of process steps is increased.
Another example of a weather strip to which this invention relates is shown in FIG. 8 and will now be described. Of course, the application of the invention is not limited to the embodiment shown.
A weather strip 1 includes: an inverted U-shaped trim portion 63, a hollow seal portion 65 formed on the apex of the trim portion 63, and a fin seal portion 67 formed on the side surface of the trim portion 63 on the outer side of an automobile. The inverted U-shaped trim portion 63 is made from rubber and has at least a pair of confronting clamp lips 69 (two pairs in FIG. 8). A metal insert 73 is embedded in trim portion 63 and maintains the clamping force thereof against automobile body flange 71. The hollow seal portion 65 and the fin seal portion 67 are made of sponge rubber in order to provide flexibility (an important factor of sealability) relative to a closure or lid portion 75 forming part of a door or trunk, or a sheet metal portion 77 of the automobile body.
To mount the weather strip 61 on the automobile body flange 71, an adhesive seal band 79 is formed by charging a seal material into the groove formed in the trim portion 63 at the innermost portion thereof. The adhesive seal band 79 seals a gap between the groove in trim portion 63 and the automobile body flange 71 not only to supplement the sealing function of the fin seal portion 67 and the clamp lips 69, but also to prevent rusting of the edge of the automobile body flange 71.
In order to increase the flexibility, and hence sealability of the above-mentioned elastic seal material, it has been proposed to use corking materials (sealants) that are amorphous and come into contact with any shape (see Japanese Utility Model Application No. 104412/1977). In addition, a viscous elastic seal material has been used and is disclosed in Japanese Utility Model Unexamined Publication No. 65209/1980 and Japanese Utility Model Examined Publication No. 31877/1986.
However, it has been found from a study conducted by the inventors that when the trim for an automobile utilizes an amorphous sealant such as described above, the following problems exist.
First, the amorphous sealant is so adhesive that much care and many process steps are involved during formation. For example, the sealant must be carefully forced out of its container and the releasable nozzle of the application gun must be carefully directed in order to avoid excessive and incorrect adhesion. The same problem is similarly encountered by the elastic seal materials.
Second, to ensure sealability, the amount of sealant charged into the groove inner portion of the trim portion must be a value larger than a predetermined value while taking into account such factors as flange height and trim assembling variations. This has made it difficult to speed up the sealant charging operation.
Third, the seal band 79 formed on the inner groove is prone to fall off the trim portion.